Liquid toner printing systems are well known. Some of such systems, utilize an intermediate transfer member. The intermediate transfer member receives a developed liquid toner image from an image forming member (“first transfer”), such as a photoreceptor, and transfers the image to a final substrate (second transfer). Such systems are designated herein as “liquid toner offset printing systems.” As used herein, the term printer includes copiers or other machines in which the final product is a printed image on a substrate.
Two methodologies are used when multi-color images are to be printed. Both require the generation of multiple separations (i.e., single color partial images) that, when superimposed, result in the desired printed image. Each of said images is separately generated on the image forming member, transferred to the intermediate transfer member and transferred therefrom to the final substrate. In some systems, the images are separately transferred to the final substrate. In these systems, the images are separate on the intermediate transfer member and are superimposed, in registration, on the final substrate. In other systems, referred to herein as “one-shot” systems, the images are separately formed on the image forming member and are transferred to the intermediate transfer member in registration and superposition thereon. The superposed images are transferred together to the final substrate.
In some one shot systems, a same image forming member is used to generate the separations sequentially. In other systems a plurality of image forming systems are present, each of which generates an image of a different color, the plurality of images being superimposed on the intermediate transfer member.
Toner systems for printing liquid toner images are also well known and have a long history. In modern liquid toner printing, the toner is based on a composition that includes a carrier liquid and (generally charged) colored (generally pigmented) polymer based toner particles. Exemplary examples of such toners are described in U.S. Pat. Nos. 6,155,457; 6,146,803; 5,972,548; 5,923,929; 5,554,476; 5,426,491; 5,407,771; 5,346,796; 5,286,593; 5,264,313; 5,266,435; 5,231,454; 5,208,130; 5,108,866; 5,048,762; 5,047,306; 4,966,824; 4,794,651; 4,794,651; 4,756, 986; 4,719,026; 4,582,774; PCT publications WO 96/31808; WO 99/45433; WO 96/13760; WO 01/53895 and WO 01/88619, the disclosures of all of which are incorporated herein by reference.
In general, the various differently colored toners in a set of toners used to print a given image have a same basic structure, namely, that the polymer used as the basis for the toner particles is the same for the entire set.